This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Despite the recent successes in structural characterization of membrane proteins by X-ray crystallography and solution NMR spectroscopy, these studies remain a challenge due to the inherent insolubility and difficulties in crystallization of many of membrane-associated proteins. As the result, our knowledge about the architecture and function of membrane proteins remains sparse. In particular, structural changes associated with activation of peripheral membrane proteins by non-substrate lipids, which are critical for the enzymatic activity of these proteins, are not understood at the atomic level because of lack of experimental methods to probe specific protein-lipid interactions. In this pilot project, we will develop new magic angle spinning solid-state NMR based methods to study the structure and function of peripheral membrane proteins. In particular, two- and three-dimensional experiments will be established to probe directly lipid-protein interactions. These experiments will be tested on a phosphatidylinositol-specific phospholipase C (PI-PLC) from Bacillus thuringiensis. With the new methods in hand, the structural basis of the interfacial activation of PI-PLC will be examined. These efforts represent the first step toward our long-term goal to elucidate the structure and the mechanism of biomedically important human phospholipases.